RF power amplifiers are key components in any high-frequency system and application. The demand for higher bandwidth and higher speeds for multimedia applications puts stringent requirements on these amplifiers such as high output power, linearity and efficiency. Amplifiers comprising bipolar transistors (such as heterojunction bipolar transistors (HBTs) are often used in preference to CMOS-based devices for RF power amplifiers because of their excellent performance at high frequencies.
R. Sorge et al., “Concept of vertical bipolar transistor with lateral drift region, applied to high voltage SiGe HBT”, SiRF, 2012 describes a vertical bipolar transistors having an additional lateral drift region introduced between a sub collector and collector contact region.